Screw pump

ABSTRACT

The improved screw pump includes a spiral flight on an inclined shaft and mounted in a trough. An upper bearing takes axial and radial thrusts. A lower bearing takes radial thrust and has a lubrication chamber and lubrication channels between its stub shaft and bush. A pump feeds a lubricant through an inlet passageway in the stub shaft. An outlet conduit connects to an outlet passageway in the stub shaft, so there are both inlet and outlet connections. In one embodiment the outlet conduit is a stand pipe with a visual lubrication indicator. In another embodiment, there is an accumulation chamber, a pressure gauge, and a pressure switch for controlling the pump.

Grujanac et a1.

[ SCREW PUMP [75] Inventors: Peter Grujanac, Bartlett; Clyde L.

Huntington, Elgin, both of 111. [73] Assignee: Lakeside Equipment Corporation,

Bartlett, Ill.

[22] Filed: Sept. 13, 1973 [21] Appl. No.: 397,065

[52] 1.1.8. C1. 415/72, 415/118 [51] Int. Cl. F03b 3/12, F03b 11/06 [58] Field of Search 417/13, 63, 900; 415/72, 415/73, 74, 75, 110, 118; 184/628 [56] References Cited UNITED STATES PATENTS 1,211,457 1/1917 Layne 415/175 1,661,360 3/1928 Clark 2,160,295 5/1939 Stewartr... 2,505,386 4/1950 Collins..... 2,960,938 1l/l960 Williams 3,073,513 l/l963 Bailey 3,796,508 3/1974 Rowley 415/72 1 1 Feb. 18, 1975 FOREIGN PATENTS OR APPLICATIONS Primary Examiner-Wil1iam L. Freeh [57] ABSTRACT The improved screw pump includes a spiral flight on an inclined shaft and mounted in a trough. An upper bearing takes axial and radial thrusts. A lower bearing takes radial thrust and has a lubrication chamber and lubrication channels between its stub shaft and bush. A pump feeds a lubricant through an inlet passageway in the stub shaft. An outlet conduit connects to an outlet passageway in the stub shaft, so there are both inlet and outlet connections. in one embodiment the outlet conduit is a stand pipe with a visual lubrication indicator. In another embodiment, there is an accumulation chamber, a pressure gauge, and a pressure switch for controlling the pump.

11 Claims, 4 Drawing Figures Pmmiunmms 3-867 057 SHEET 20F 2. I

SCREW PUMP BACKGROUND The invention pertains to pumps and more particularly to screw pumps.

The screw pump is by far the oldest type of pump, being invented by Archimedes in the third century B.C. After the piston pump and centrifugal pump were developed, the screw pump was considered obsolete. Operating experience, however, proved that the centrifugal pump had serious shortcomings when handling heavily contaminated waste water. The inherent advantages of the screw pump, or spiral pump, has led to more widespread use. A prime advantage is the screw pumps built-in variable capacity. Pumping rate automatically adjusts to the depth of liquid in the inlet chamber. Operation is continuous and speed is constant. Screw pumps are efficient over a wide range and lifts of up to 30 feet are practical. They require no prescreening and pass any debris as large as the gap between screw flights. Larger objects do not clog the pump; they are rejected. Screw pumps are useful for pumping return sludge from the clarifier back to the aeration basin in activated sludge treatment. The spiral lift handles the activated sludge floc gently and reduces disintegration of the floc.

In a screw pump, the lower bearing is frequently mounted in the inlet chamber, below the liquid level thereat. Lubricating the bearing is a problem, and operating conditions are severe. It is desirable to provide an improved screw pump which assures proper lubrication of the lower bearing.

SUMMARY The present invention relates generally to screw pumps of the Archimedes type and, more particularly, to a screw pump having an improved bearing construction with lubrication means.

It is a general object of the present invention to provide a screw pump with an improved bearing construction.

Another object of the invention is to provide an improved screw pump which assures proper lubrication of the lower bearing.

A further object is to provide a screw pump in accordance with the foregoing objects in which the bearing is provided with a flowthrough lubrication system.

Another object is to provide a screw pump in accordance with the foregoing object in which the sytem includes inlet and outlet connections.

Yet another object is to provide a screw pump with a lower bearing construction which has continuous pressure on the lubricant in the bearing area.

lt is another object to provide a screw pump in accordance with the foregoing object with apparatus for maintaining a continuous pressure on the lubricant and for automatically feeding additional lubricant to the bearing when required.

Still another object of the invention is to provide a screw pump with novel lubrication connections at the bearing.

These, and other objects and advantages of the present invention, will become apparent as the same becomes better understood from the following detailed description when taken in conjunction with the accompanying drawings.

DRAWINGS P16. 1 is a side elevation of a screw pump constructed in accordance with the present invention and showing the trough in section;

FlG. 2 is a view, on a larger scale than FlG. 1, showing the screw flights in elevation, the lower bearing in partial section, and the lubrication system diagrammatically;

FIG. 3 is a greatly enlarged view of the lower bearing construction, partly elevational and partly in section. and showing another embodiment of the outlet connection; and

FIG. 4 is a cross-sectional view taken generally along line 44 of FIG. 1.

DESCRlPTlON Reference is now made more particularly to the drawings which illustrate the best presently known mode of carrying out the invention and wherein similar reference characters indicate the same parts throughout the several views.

The screw pump includes an elongate shaft in the form of a hollow revolving steel tube 10 to which is mounted one or more spiral flights 11 also made of steel and continuously welded to the tube 10. Upper and lower end plates 12 and 13 are welded to the ends of the tube 10. The portion thus far described is rotatably mounted in an inclined concrete trough 15 which may be constructed in multiple pours of concrete as shown in FIG. 4. A steel deflector plate 16 is mounted on the trough 15 and curves around the upper section of the spiral flights 11 to prevent spills as the pump 0perates.

A steel base plate 18 is mounted, as by anchor bolts, at an inclined angle on the top of a concrete pedestal 19. An upper bearing assembly, generally designated 20 in FIG. 1, is bolted to base plate: 18. It is a dual bearing which takes both the axial and radial thrust loads. The upper bearing assembly 20 conveniently has a cast housing which is provided with a double seal (not shown) to protect the bearing from any foreign materials. A stub shaft 21, supported by the upper bearing assembly 20, has a driving connection to end plate 12. A motor 22 drives the shaft through a double reduction helical gear reducer 24 and a flexible coupling 26. Other drive arrangements may also be used, if desired.

The lower bearing, generally designated 30, is mounted in the influent chamber of the pump. The lower bearing is a grease lubricated sleeve-type bearing which is totally enclosed, and automatically lubricated. It is designed to absorb radial forces while accommodating changes in length of the tube 10 caused by expansion or contraction.

The lower bearing 30 includes a base 32 forming a cradle 33 (see FIG. 3). A T-shaped shaft includes a cylindrical member 36 supported in the cradle 33 and a stub shaft 37 advantageously coaxial with the tube 10. The cylindrical member 36 and the cradle 33 cooperate to allow angular adjustment of the screw during installation. The angular position is then secured by means of a plurality of set screws 38. The cradle 33 is advantageously longer than the cylindrical member 36 to accommodate horizontal adjustment of the cylindrical member during installation. Opposite end plates 42, bolted on the base 32, are at opposite ends of the cradle 33 and carry a set screw 43 for fixing the horizontal position of the cylindrical member 36.

Circumjacent the stub shaft 37 is a bronze bush 46. A plurality of lubrication channels 47, advantageously four in number and disposed 90 apart, are recessed into the inner surface of the bush and extend from the upper end to adjacent the lower end of the bush. Greater or lesser numbers of channels may be used, if desired. If the stub shaft 37 is about 4 inch in diameter. for example, the lubrication channels 47 may be about A inch in width and /8 inch deep. A hollow cylindrical housing 48 closely surrounds the bush 46 and is welded to a mounting plate 49 which is bolted to the end plate 13, as best seen in FIG. 3. At the lower end of the cylindrical housing 48 is a shaft seal 51 which engages the stub shaft and helps prevent water from entering the hearing. A steel shield 54 is mounted on the base 32 to guard the lower bearing from deleterious debris.

Referring particularly to FIG. 3, it can be seen that the upper end of the stub shaft 37 is spaced from the end plate 13 to form a lubrication chamber 56 which communicates with the lubrication channels 47. An axial passageway 58 in the stub shaft 37 communicates with the lubrication chamber 56 and extends therefrom to the axis of the cylindrical member 36. At that point the passageway 58 turns at right angles to the extremity of the cylindrical member 36 where it is coupled to an inlet conduit 59. Advantageously, the portion of the first passageway 58 in the cylindrical member 36 is axially located so that the inlet conduit 59 may be connected without regard to the angular position of the stub shaft 37. The stub shaft 37 is also bored with an eccentric passage 62 which is located at the seal end of the assembly. A second passageway 63, 64 extends to the exterior of the stub shaft and is connected to an outlet conduit 66.

Grease, or other lubricant, is delivered from a pump P, through the inlet conduit 59 to the cylindrical member 36. From that connection, it-passes through first passageway 58 to the lubrication chamber 56 and then is dispersed throughout the bearing cavity by means of the lubrication channels 47. The outlet passageway 62-64, connected to outlet conduit 66, assures the presence of lubricant throughout the entire bearing assembly. In other words, the lubricant has to pass completely over the bearings to reach the outlet conduit 66. In the embodiment shown in FIG. 3, the outlet conduit 66 is in the form of a stand pipe having a window at 68 which provides a visual indication of lubricant reaching that point.

In the embodiment diagrammatically illustrated in FIG. 2, the outlet conduit 66 is connected to an externally mounted pressure switch 72, a pressure gauge 74, and a capacity volume chamber or accumulation chamber 76. The purpose of the accumulation chamber 76 is to provide a pneumatic cushion for the hydraulic system so that, when the pump P is turned off, a static head equal to the pressure applied by the pneumatic cushion continues to maintain a back pressure on the lubricant in the bearing assembly. With pressure applied to the lubricant by the pneumatic cushion, lubricant will continue to have a tendency to be dissipated through the shaft seal 51. thereby precluding a flow of fluid into the bearing. The pressure switch 72 is set to maintain the lubricant pressure within preselected limits by controlling the starting and stopping of the pump P. In this manner, the lubricant is automatically fed to the lower bearing and the lubricant is under continuous pressure even though the pump is cyclically operated. The pressure gauge 74 advantageously provides a visual indication of the pressure on the lubricant.

A second pressure switch. similar to switch 72, may also be provided to complete a circuit to an alarm device should the grease pressure drop to an unacceptably low level. This situation could be caused. for example, by a faulty shaft seal 51. a break in conduits 59 or 66, or emptying of the reservoir of the grease pump P.

While preferred embodiments of the invention have herein been illustrated and desired, this has been done by way of illustration and not limitation, and the invention should not be limited except as required by the scope of the appended claims.

What is claimed is;

l. A screw pump including an elongate shaft inclined to the horizontal and having upper and lower ends, an upper bearing and a lower bearing supporting the shaft for rotation, and a spiral flight extending along the elongate shaft for raising a liquid as the elongate shaft is rotated; characterized in that the lower bearing comprises a stub shaft coaxial with the elongate shaft; a bush circumjacent the stub shaft and connected to the elongate shaft for rotation therewith; means providing a lubrication channel between the bush and stub shaft; means including an inlet passageway through the stub shaft for providing an inlet connection to the lubrication channel; a pump operatively connected to the inlet passageway for feeding a lubricant under pressure to the lubrication-channel; an outlet passageway through the stub shaft providing an outlet connection to the lubrication channel; an outlet conduit connected to the outlet passageway; a pressure switch responsive to the pressure on the lubricant in the outlet conduit for starting and stopping the pump to maintain the pressure on the lubricant without preselected limits.

2. A screw pump as set forth in claim 1, including an accumulation chamber communicating with the outlet conduit for receiving a quantity of the lubricant therefrom and having a pneumatic cushion to provide back pressure on the lubricant when the pump is stopped.

3. A screw pump as set forth in claim 1, including a pressure gauge operatively connected to the outlet con duit to provide a visual indication of the pressure on the lubricant.

4. A screw pump including an elongate shaft inclined to the horizontal and having upper and lower ends, an upper bearing and a lower bearing supporting the shaft for rotation, and a spiral flight extending along the elongate shaft for raising a liquid as the elongate shaft is rotated; characterized in that the lower bearing comprises a stub shaft coaxial with the elongate shaft and having an upper end spaced from the lower end of the elongate shaft to form a lubrication chamber; a rotatable bush circumjacent the stub shaft and having a lower end; means operatively connecting the bush to the elongate shaft for rotation therewith; means providing a lubrication channel between the bush and stub shaft; the lubrication channel communicating with the lubrication chamber and extending therefrom to adjacent the lower end of the bush; a first passageway through the stub shaft extending from the exterior of the stub shaft to the lubrication chamber; a second passageway extending from the exterior of the stub shaft to adjacent and lower end of the bush and communicating with the lubrication channel; and outlet conduit connected to one of the passageways; a lubricant indicator associated with the outlet conduit; means for supplying lubrication under pressure to the other passageway and through the lubrication chamber and channel to said one passageway, and through the one passageway and the outlet connection to the lubricant indicator; whereby lubricant flows through the lower bearing to the lubricant indicator.

5. A screw pump as set forth in claim 1 including a hollow cylinder closely surrounding the bush and mounted on the lower end of the elongate shaft, and a shaft seal mounted on the hollow cylinder at the lower end of the bush and engaged with the stub shaft.

6. A screw pump as set forth in claim 1 wherein the lower bearing includes a cylindrical member at right angles to the stub shaft; the cylindrical member being affixed to the lower end of the stub shaft so that the assemblage is in an inverted T-shape; a base forming a cradle for receiving the cylindrical member at various angular positions of th stub shaft, thereby forming an adjustable bearing assembly; and wherein the passageway extends through the stub shaft and then at a right angle axially of the cylindrical member so that the conduit may be connected without regard to the angular position of the stub shaft.

7. A screw pump as set forth in claim 1 wherein the outlet conduit is in the form of a stand pipe extending to a level above the liquid level at the lower end of the elongate shaft; and the lubricant indicator is a visual indicator on the stand pipe above said liquid level.

8. A screw pump as set forth in claim 1 wherein the means for supplying lubrication under pressure includes a pump and an inlet conduit connecting the pump and said other passageway; and including an accumulation chamber communicating with the outlet conduit for receiving a quantity of lubricant therefrom and having a cushion of air under pressure to provide pressure on the lubricant back toward the lower bearing when the pump is stopped.

9. A screw pump as set forth in claim 8, including a pressure switch for starting and stopping the pump to maintain the pressure on the lubricant between preselected limits.

10. A screw .pump as set forth in claim 9, including a pressure gauge operatively connected to the outlet conduit to provide a visual indication ofthe pressure on the lubricant.

11. A screw pump including an elongate shaft having upper and lower ends and a spiral flight extending along the shaft; combined radial and axial thrust bearing means at the upper end of the shaft and radial thrust bearing means at the lower end of the shaft supporting the shaft for rotation; an inclined trough in which the spiral flight is located; drive means for rotating the shaft and spiral flight in the trough to raise liquid therealong; characterized in that the radial thrust bearing at the lower end of the shaft comprises a stub shaft coaxial with the elongate shaft and having an upper end spaced from the lower end of the elongate shaft to form a lubrication chamber; a cylindrical member affixed at right angles to the lower end of the stub shaft so that the assemblage is in an inverted T-shaped; a base forming a cradle receiving the cylindrical member at various angular positions of the stub shaft, thereby forming a bearing assembly which is adjustable during installation to accommodate various angles of the trough; a rotatable bushing circumjacent the stub shaft; and having a lower end; means operatively connecting the bushing to the elongate shaft for rotation therewith; a plurality of lubrication channels recessed into the inner surface of the bushing; the lubrication channels communicating with the lubrication chamber and extending therefrom to adjacent the lower end of the bushing; a passageway extending longitudinally of the stub shaft from the lubrication chamber to the cylindrical member and then longitudinally thereof to an axially located terminus atone end of the cylindrical member, whereby adjusting the position of the stub shaft has no effect on the position of the terminus of the passageway; a conduit connected at the terminus of the passageway; and a pump for feeding lubricant under pressure through said conduit and passageway.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. '1 3,867,657 I I DATED 1 February 18 1975 'NVENT0R(5) 1 Peter Grujanao and Clyde L. Huntington It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1, last line, "without" should be within Claim 4, line 21, "and" shouid be an Claim 5, line 1, "1" should be 1+ Claim 6, line l, 'l" should be L;

Claim 7, line 1, "1""shou1d be L Claim 8, line 1, "1" should be L;

Claim 11, line 15, "T-shaped" should be T-shape Signed and sealed this 10th day of June 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attescing Officer 1 and Trademarks 

1. A screw pump including an elongate shaft inclined to the horizontal and having upper and lower ends, an upper bearIng and a lower bearing supporting the shaft for rotation, and a spiral flight extending along the elongate shaft for raising a liquid as the elongate shaft is rotated; characterized in that the lower bearing comprises a stub shaft coaxial with the elongate shaft; a bush circumjacent the stub shaft and connected to the elongate shaft for rotation therewith; means providing a lubrication channel between the bush and stub shaft; means including an inlet passageway through the stub shaft for providing an inlet connection to the lubrication channel; a pump operatively connected to the inlet passageway for feeding a lubricant under pressure to the lubrication channel; an outlet passageway through the stub shaft providing an outlet connection to the lubrication channel; an outlet conduit connected to the outlet passageway; a pressure switch responsive to the pressure on the lubricant in the outlet conduit for starting and stopping the pump to maintain the pressure on the lubricant without preselected limits.
 2. A screw pump as set forth in claim 1, including an accumulation chamber communicating with the outlet conduit for receiving a quantity of the lubricant therefrom and having a pneumatic cushion to provide back pressure on the lubricant when the pump is stopped.
 3. A screw pump as set forth in claim 1, including a pressure gauge operatively connected to the outlet conduit to provide a visual indication of the pressure on the lubricant.
 4. A screw pump including an elongate shaft inclined to the horizontal and having upper and lower ends, an upper bearing and a lower bearing supporting the shaft for rotation, and a spiral flight extending along the elongate shaft for raising a liquid as the elongate shaft is rotated; characterized in that the lower bearing comprises a stub shaft coaxial with the elongate shaft and having an upper end spaced from the lower end of the elongate shaft to form a lubrication chamber; a rotatable bush circumjacent the stub shaft and having a lower end; means operatively connecting the bush to the elongate shaft for rotation therewith; means providing a lubrication channel between the bush and stub shaft; the lubrication channel communicating with the lubrication chamber and extending therefrom to adjacent the lower end of the bush; a first passageway through the stub shaft extending from the exterior of the stub shaft to the lubrication chamber; a second passageway extending from the exterior of the stub shaft to adjacent and lower end of the bush and communicating with the lubrication channel; and outlet conduit connected to one of the passageways; a lubricant indicator associated with the outlet conduit; means for supplying lubrication under pressure to the other passageway and through the lubrication chamber and channel to said one passageway, and through the one passageway and the outlet connection to the lubricant indicator; whereby lubricant flows through the lower bearing to the lubricant indicator.
 5. A screw pump as set forth in claim 1 including a hollow cylinder closely surrounding the bush and mounted on the lower end of the elongate shaft, and a shaft seal mounted on the hollow cylinder at the lower end of the bush and engaged with the stub shaft.
 6. A screw pump as set forth in claim 1 wherein the lower bearing includes a cylindrical member at right angles to the stub shaft; the cylindrical member being affixed to the lower end of the stub shaft so that the assemblage is in an inverted T-shape; a base forming a cradle for receiving the cylindrical member at various angular positions of th stub shaft, thereby forming an adjustable bearing assembly; and wherein the passageway extends through the stub shaft and then at a right angle axially of the cylindrical member so that the conduit may be connected without regard to the angular position of the stub shaft.
 7. A screw pump as set forth in claim 1 wherein the outlet conduit is in the form of a stand pipe extending to a level above the liquid level at the lower enD of the elongate shaft; and the lubricant indicator is a visual indicator on the stand pipe above said liquid level.
 8. A screw pump as set forth in claim 1 wherein the means for supplying lubrication under pressure includes a pump and an inlet conduit connecting the pump and said other passageway; and including an accumulation chamber communicating with the outlet conduit for receiving a quantity of lubricant therefrom and having a cushion of air under pressure to provide pressure on the lubricant back toward the lower bearing when the pump is stopped.
 9. A screw pump as set forth in claim 8, including a pressure switch for starting and stopping the pump to maintain the pressure on the lubricant between preselected limits.
 10. A screw pump as set forth in claim 9, including a pressure gauge operatively connected to the outlet conduit to provide a visual indication of the pressure on the lubricant.
 11. A screw pump including an elongate shaft having upper and lower ends and a spiral flight extending along the shaft; combined radial and axial thrust bearing means at the upper end of the shaft and radial thrust bearing means at the lower end of the shaft supporting the shaft for rotation; an inclined trough in which the spiral flight is located; drive means for rotating the shaft and spiral flight in the trough to raise liquid therealong; characterized in that the radial thrust bearing at the lower end of the shaft comprises a stub shaft coaxial with the elongate shaft and having an upper end spaced from the lower end of the elongate shaft to form a lubrication chamber; a cylindrical member affixed at right angles to the lower end of the stub shaft so that the assemblage is in an inverted T-shaped; a base forming a cradle receiving the cylindrical member at various angular positions of the stub shaft, thereby forming a bearing assembly which is adjustable during installation to accommodate various angles of the trough; a rotatable bushing circumjacent the stub shaft; and having a lower end; means operatively connecting the bushing to the elongate shaft for rotation therewith; a plurality of lubrication channels recessed into the inner surface of the bushing; the lubrication channels communicating with the lubrication chamber and extending therefrom to adjacent the lower end of the bushing; a passageway extending longitudinally of the stub shaft from the lubrication chamber to the cylindrical member and then longitudinally thereof to an axially located terminus at one end of the cylindrical member, whereby adjusting the position of the stub shaft has no effect on the position of the terminus of the passageway; a conduit connected at the terminus of the passageway; and a pump for feeding lubricant under pressure through said conduit and passageway. 